Unidentified gunmen have kidnapped three workers from the United Nation's refugee agency in Sudan's restive Darfur region, a local official told Reuters on Monday.

The three workers, one Sudanese and two Nepalese, were kidnapped from Geneina, the capital of West Darfur state and were taken to an unknown location, said West Darfur government spokesman Abdallah Gar al-Nabi.

Security forces were working to retrieve them and locate the culprits, he added. An official from the United Nations High Commissioner for Refugees (UNHCR) declined to comment.

Security remains fragile in Darfur, where mainly non-Arab tribes have been fighting the Arab-led government in Khartoum, and the government is struggling to control rural areas.

Some 300,000 people have been killed in Darfur since the conflict began in 2003, the United Nations says, while over 2.5 million have been displaced.

The International Criminal Court issued arrest warrants for Sudanese President Omar Hassan al-Bashir in 2009 and 2010 on charges of war crimes and genocide in his drive to crush the Darfur revolt.